1. Field of the Invention
The present invention relates to "strut" or "baulking ring" type synchronizers for synchronized change gear transmissions. In particular, the present invention relates to an improved sliding clutch sleeve/dent mechanism for strut type synchronizers.
2. Description of the Prior Art
Fully or partially synchronized change gear transmissions for automobiles and for trucks are well known in the prior art as may be seen by reference to U.S. Pat. Nos. 4,989,706; 5,069,079; 4,754,665; 4,569,252; 4,502,346; 4,432,251 and 4,428,469, the disclosures of which are incorporated herein by reference.
Double acting so-called "strut" or "baulking ring" type synchronizer jaw clutch assemblies wherein a sliding clutch member is axially displaceable in either axial direction from an axially centered position to engage a selected one of two selectable gears to a shaft are well known in the prior art as may be seen by reference to U.S. Pat. Nos. 4,185,725 and 4,059,178 and published U.K. Patent Application No. 2,029,519A, the disclosures of all of which are incorporated herein by reference.
Generally, strut type synchronizers include a sliding clutch member or sleeve carrying a set of jaw clutch teeth and rotationally fixed to a shaft which sleeve is selectively axially displaceable from a neutral or nonengaged position to positively engage a complementary set of jaw clutch teeth rotationally fixed to a gear thereby to rotationally couple the gear to the shaft. Typically a baulking ring is interposed the clutch teeth of the sliding clutch sleeve and the selected gear to prevent or block axial movement of the clutch sleeve into an engaging position until substantially synchronous conditions exist. A pair of friction surfaces (usually conical) associated with the shaft (usually with the baulking ring) and the gear are provided to cause synchronous conditions as the clutch sleeve is urged toward engagement with the selected gear. The axial force urging the friction surfaces into engagement is typically generated by the baulking ring as it blocks axial movement of the sliding clutch sleeve in sensed nonsynchronous conditions.
In synchronized clutch assemblies of this type, especially in double acting clutch assemblies, it is desirable to provide a detent for the clutch sleeve sliding movement between the two gear engagement positions, so that an intermediate neutral position can be stably found. Typically, the sleeve when in a position corresponding to neutral, or when passing through neutral, presents a radially inwardly facing neutral defining recess to a nominally axially fixed radially outwardly sprung rolling detent member which tends to spring into the neutral recess, but when not in neutral, the sleeve presents a more or less smooth surface thereof to ride axially over the rolling member, revolving it. The latter must be free to roll, and it must have radial freedom to enter the neutral recess. Unfortunately it is therefore prone also to some axial freedom which, though small, can be undesirable.
A problem is that the rolling member (roller or ball) can escape from under the clutch sleeve when the sleeve has been fully slid in one or the other axial direction for engaging a gear. This problem is enhanced by the fact that the sleeve must have some tilting freedom, so that its clutch teeth or splines can always enter gaps in the clutch teeth or splines of the gears. The tilting can facilitate escape of the roller, which can prejudicially load or even wear other clutch components. The present invention aims to avoid escape of the rolling member without encouraging tilting of the sleeve.